6-(1H-1,2,3-Triazol-1-yl)- 4,7-dihydro-1,3,5-dioxazepines: A new heterocyclic system
M. V. Dubovis 1 , G. F. Rudakov 1 , A. S. Kulagin 1 , and V. F. Zhilin 1
D. Mendeleev University of Chemical Technology of Russia, 9 Miusskaya Sq., Moscow 125047,
Russia
E-mail: mdubovis@gmail.ru
Deoxygenation of primary and secondary nitroalkanes in the presence of organic trivalent phosphorus derivatives lead to the formation of nitriles, amines, and derivatives of oximes [1].
There is insufficient information available about the reactivity of tertiary nitro compounds in similar conditions.
In this work, for a series of 1-(5-nitro-1,3-dioxan-5-yl)-1 H1,2,3-triazole derivatives ( 1a–i ), we studied the possibility of nitro group transformation by the action of triethyl phosphite. It was found that 1,3-dioxane cycle expands to 4,7-dihydro-1,3,5-dioxazepines ( 2a–i ) when heated in benzene with an excess of reducing agent [2].
R
3
O
2
N N
N
N
P(OEt)
3
O
R
1
O
1a-i
R
2
C
6
H
6
, t
R
3
N
N
O
R
1
2a-i
O
R
2
N N
1,2 a R
1 c R e R
1
1
= R
3 g R
1 i R
1
= R
2
= R
3
= H, b R
1
= R
3
= H, R
2
= Ph, d R
1
= Me, R
= R
2
= R
2
2
= Et, R
3
= -(CH
2
)
4
-, R
= H, f R
1
3
= H, h R
= Me, R
3
= SiMe
3
= R
2
= H, R
2
= Me,
= Me, R
3
= H,
= R
1
2
= Me, R
= R
2
3
= -(CH
= Ph,
2
)
5
-, R
3
= H,
Deoxygenation reactions in the studied series of compounds were apparently stepwise and occurred analogously to deoxygenation of geminal chloronitrocycloalkanes with triphenylphosphine [3]. The performed study showed that 1-(5-nitro-1,3-dioxan-5-yl)-1 H1,2,3triazoles reacted with triethyl phosphite without noticeable heat effect or changes in the color of solution, which is not characteristic to deoxygenation of nitroso compounds. Thus, the most probable mechanism of dioxane ring expansion does not include a stage of nitrene formation.
The developed method can be used for the preparation of previously unavailable 4,7dihydro-1,3,5-dioxazepines, enabling characterization of the properties and reactivity of 1,3,5dioxazepine ring containing a triazole substituent at position 6.
References
1.
K. S. Kim, E. Y. Hurh, J. N. Youn, and J. I. Park, J. Org. Chem.
, 64, 9272 (1999).
2.
G. F. Rudakov, M. V. Dubovis, A. S. Kulagin, K. V. Tsar'kova, A. S. Goloveshkin and V. F. Zhilin, Chem.
Heterocycl. Compd ., 50, 11, 1634 (2015).
3.
M. Ohno, N. Kawabe, Tetrahedron Lett.
, 7, 3935 (1966).